Wheeled work machine

ABSTRACT

A wheel type work machine having improved ease of assembly and a compact-sized traveling system power transmission mechanism. The wheeled work machine comprises a traveling body ( 2 ) having an engine ( 7 ) mounted at the rear of a machine frame ( 6 ) supported by front and rear wheels ( 4, 5 ) and the traveling system power transmission mechanism ( 8 ) for transmitting power from the engine ( 7 ) to the rear wheels ( 5 ). The traveling system power transmission mechanism ( 8 ) comprises a rear wheel differential device ( 38 ) disposed on the front side of the engine ( 7 ), a hydrostatic transmission ( 35 ) disposed on the front side and the rear wheel differential device and receiving the power from the engine ( 7 ), and a mechanical transmission device ( 37 ) disposed between the hydrostatic transmission ( 35 ) and the rear wheel differential device ( 38 ) and transmitting the power from the hydrostatic transmission ( 35 ) to the rear wheel differential device ( 38 ). The rear wheel differential device ( 38 ), the mechanical transmission device ( 37 ), and the hydrostatic transmission ( 35 ) are formed integrally with the engine ( 7 ).

TECHNICAL FIELD

The present invention relates to a wheeled work machine.

BACKGROUND ART

Conventional wheeled work machines include those provided with atraveling body in which an engine is mounted at the rear of a machineframe supported by front and rear wheels, and the traveling body isprovided with a traveling system power transmission mechanism fortransmitting power from the engine to the rear wheels, wherein arotation table is supported on the traveling body so as to be able toswivel about a vertically oriented steering axis, a ground implement isprovided to the front part of the rotation table, a driver seat isprovided to the rear part, and a steering device for the travelingsystem and a steering device for the ground implement are provided tothe rotation table (see Patent Document 1).

The traveling system power transmission mechanism has a rear wheeldifferential device, a hydrostatic transmission to which the power fromthe engine is transmitted, and a mechanical transmission device fortransmitting power from the hydrostatic transmission to the rear wheeldifferential device.

-   [Patent Document 1] Japanese Laid-open Patent Application No.    2005-171608

DISCLOSURE OF THE INVENTION Problems that the Invention is Intended toSolve

In conventional work machines, the engine, the rear wheel differentialdevice, the hydrostatic transmission, and the mechanical transmissiondevice are individually attached to the machine frame, and the ease ofassembly is poor.

There is also a need to make the traveling system power transmissionmechanism compact.

In view of the foregoing, an object of the present invention is toprovide a wheeled work machine in which ease of assembly is enhanced,and the traveling system power transmission mechanism is made compact.

Means for Solving the Problems

A first aspect of the present invention designed to solve theabove-mentioned problems is a wheeled work machine comprising atraveling body having an engine mounted at a rear part of a machineframe supported by front and rear wheels, and a traveling system powertransmission mechanism for transmitting power from the engine to therear wheels, wherein the traveling system power transmission mechanismhas a rear wheel differential device disposed in front of the engine, ahydrostatic transmission that is disposed in front of the rear wheeldifferential device and receives power from the engine, and a mechanicaltransmission device that is disposed between the hydrostatictransmission and the rear wheel differential device and transmits powerfrom the hydrostatic transmission to the rear wheel differential device;and the engine, the rear wheel differential device, the mechanicaltransmission device, and the hydrostatic transmission are formedintegrally with each other.

A configuration may be adopted in which a housing that accommodates therear wheel differential device is attached and fixed to a front surfaceof the engine, a transmission case that accommodates the mechanicaltransmission device is attached and fixed to a front surface of thehousing, and a casing for the hydrostatic transmission is attached andfixed to a front surface of the transmission case.

A configuration may be adopted in which the power transmission mechanismhas left and right final transmission devices for transmitting powerfrom left and right differential output shafts of the rear wheeldifferential device to rear wheel axles on same left and right sides,and final transmission cases that accommodate the final transmissiondevices are attached and fixed to the housing.

The wheeled work machine may comprise a rotation table supported so asto be able to swivel on the traveling body, wherein a ground implementis provided to a front part of the rotation table, and a driver seat isprovided to a rear part of the rotation table.

A configuration may be adopted in which the machine frame has an upperwall and left and right side walls that extend downward from left andright ends of the upper wall; an engine positioning part for positioningthe engine at a rear part between the left and right side walls; atravelling power transmission system positioning part for positioningthe housing, the transmission case, and the casing in front of theengine between the left and right side walls; and a bearing positioningpart for positioning a swivel bearing for supporting the rotation tablein a substantial center position between front and rear axles; wherein acase fitting part for fitting with the final transmission cases fromabove is formed at rear parts of the left and right side walls.

A rear wheel axle that receives power from the differential outputshafts of the rear wheel differential device and rotates the rear wheelsmay also be provided behind the differential output shafts so as tooverlap the engine as viewed from the side.

According to the present invention, the rear wheel differential device,the mechanical transmission device, and the hydrostatic transmission areattached to, and integrated with, the engine, and the ease of assemblyis therefore enhanced.

Since the rear wheel differential device, the hydrostatic transmission,and the mechanical transmission device of the traveling system powertransmission mechanism are all formed in front of the engine, thetraveling system power transmission mechanism can be made compact.

The work machine can also be made compact in the front-rear direction byproviding the rear wheel axle that receives power from the differentialoutput shafts of the rear wheel differential device and rotates the rearwheels behind the differential output shafts and overlapping the engineas viewed from the side.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a left side view showing the wheeled swiveling work machine;

FIG. 2 is a front view showing the swiveling work machine;

FIG. 3 is a perspective view showing the traveling body and the rotationtable;

FIG. 4 is a plan view showing the traveling body;

FIG. 5 is a left side view showing the traveling body;

FIG. 6 is a left side view showing the rear upper part of the travelingbody and the rear lower part of the rotating body;

FIG. 7 is a plan view showing the rear wheels and the traveling systempower transmission mechanism;

FIG. 8 is a magnified plan view showing the traveling system powertransmission mechanism and the surrounding area;

FIG. 9 is a plan view showing the machine frame;

FIG. 10 is a left side view showing the machine frame;

FIG. 11 is a front view showing the machine frame, and a back viewshowing the machine frame;

FIG. 12 is a left side view showing the front wheel axle case and thepivot locking mechanism;

FIG. 13 is a front view showing the front wheel axle case, and a frontsectional view showing the swivel locking mechanism;

FIG. 14 is a front view showing the front wheel axle case and the swivellocking mechanism;

FIG. 15 is an exploded front view showing the front wheel axle case andthe swivel locking mechanism;

FIG. 16 is a plan view showing the excavating implement;

FIG. 17 is a back view showing the bucket;

FIG. 18 is a left side view showing the bucket and arms;

FIG. 19 is a sectional view showing the rotation means;

FIG. 20 is a plan view showing the orientation maintaining means, and aback view showing the orientation maintaining means;

FIG. 21 is a plan view, a back view, and a sectional view showing therotation restriction means;

FIG. 22 is a plan view showing the driver seat and the surrounding area;

FIG. 23 is a left side view showing the driver seat and the surroundingarea;

FIG. 24 is a plan view showing the rotation table;

FIG. 25 is a left side view showing the rotation table;

FIG. 26 is a left side view showing the area below the driver seat;

FIG. 27 is another left side view showing the area below the driverseat;

FIG. 28 is a front view showing the rotation axis and the surroundingarea;

FIG. 29 is a plan view showing the operation of the detection mechanismand the operating means;

FIG. 30 shows the hydraulic circuit on the side of the traveling body;and

FIG. 31 shows the hydraulic circuit on the side of the rotating body.

KEY

-   -   2 traveling body    -   4 front wheels    -   5 rear wheels    -   6 machine frame    -   7 engine    -   8 traveling system power transmission mechanism    -   11 engine positioning part    -   16 rotation bearing    -   18 upper wall    -   19 side walls    -   35 hydrostatic transmission    -   37 mechanical transmission device    -   38 rear wheel differential device    -   39 rear wheel axles    -   40 final transmission devices    -   43 casing    -   53 differential output shafts    -   61 housing    -   62 transmission case    -   63 traveling power transmission system positioning part    -   64 case fitting parts    -   67 final transmission cases    -   70 foot brake means    -   71 drive-wheel brake means    -   86 bearing positioning part    -   91 upper wall    -   92 side walls    -   201 rotation table    -   202 steering device    -   203 excavating implement    -   204 driver seat positioning frame    -   205 driver seat    -   206 operating devices    -   X rotation axis

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described hereinafter withreference to the drawings.

In FIGS. 1 through 5, the reference numeral 1 indicates anurban-oriented small-sized wheeled swiveling work machine that is usedfor gardening or the like, for example. The swiveling work machine 1 isgenerally composed of a lower traveling body 2 and an upper rotatingbody 3.

The traveling body 2 is a wheeled traveling body 2 that is enabled totravel by a pairs of left and right front and rear wheels 4, 5, and isprovided with the pairs of left and right front and rear wheels 4, 5, amachine frame 6 supported by the front and rear wheels 4, 5, an engine 7mounted on the machine frame 6, a traveling system power transmissionmechanism 8 for transmitting the power from the engine 7 to the rearwheels 5, and a front wheel drive system 33 for branching from thetraveling system power transmission mechanism 8 and transmitting powerto the front wheels 4.

As shown in FIGS. 1 through 13, the machine frame 6 is primarilycomposed of a main frame 9 and a front frame 10 that is provided to thefront of the main frame 9. The engine 7, a radiator 12, a battery 13, aswivel joint 14, a swiveling motor 15, a rotation bearing 16, and othercomponents are mounted to the main frame 9. A fuel tank 17 for storingfuel for the engine 7 is mounted to the front frame 10, the rear part ofthe main frame 9 is supported by the left and right rear wheels 5, andthe front part of the front frame 10 is supported by the left and rightfront wheels 4 and made capable of traveling.

The main frame 9 is composed of a sheet material, and is primarilycomposed of an upper wall 18, left and right side walls 19 that extenddownward from the left and right edges of the upper wall 18, a frontwall 20 fixed to the front ends of the upper wall 18 and the left andright side walls 19, and a rear wall 21 for connecting the lower rearend parts of the left and right side walls 19 to each other. The mainframe 9 is formed in a downward-opening shape.

The engine 7 is longitudinally positioned in the left-right center ofthe rear part between the left and right side walls 19 of the main frame9 so that the axis of the crank shaft is in the front-rear direction andan output shaft 23 protrudes to the front. A cut-out opening 24 isformed in the upper wall 18 so that the upper end of the engine 7protrudes upward from the upper wall 18 of the main frame 9, and acooling fan 25 is provided to the rear part of the engine 7.

The rear part of the main frame 9 between the left and right side walls19 is an engine positioning part 11 for positioning the engine 7. Theradiator 12 is disposed on the left side of the engine 7 and attachedand fixed to the main frame 9, and the battery 13 is disposed on theright side of the engine 7 and attached and fixed to the main frame 9.

The left and right sides of the main frame 9 are covered by side covers26. The rear part of the main frame 9 is covered by a fixed cover 28provided with rear-wheel fenders 27 for covering the left and right rearwheels 5 that connects the front parts of the left and right rear-wheelfenders 27 to each other, an opening and closing cover 29 capable ofopening and closing that is disposed between the rear parts of the leftand right rear wheel fenders 27 that covers the upper side of the rearpart of the engine 7, and a rear bumper cover 30 for covering the backsurface of the main frame 9.

The space between the rear end of the opening and closing cover 29 andthe upper end of the rear bumper cover 30 is open, and through this openportion, the cooling fan 25 discharges the air inside the enginecompartment or draws outside air into the engine compartment.

The front frame 10 is covered by a cover member 31 having front wheelfenders for covering the left and right front wheels 4; and a frontbumper cover 41 for covering the front surface of the front frame 10.

The traveling system power transmission mechanism 8 is provided with atraveling drive shaft 34 to which power from the engine 7 istransmitted; a hydrostatic transmission (“HST” hereinafter) 35 to whichpower is transmitted from the traveling drive shaft 34; a mechanicaltransmission device 37 for transmitting the power from the HST 35 to abevel pinion shaft 36; a rear wheel differential device 38 to whichpower is transmitted from the bevel pinion shaft 36; and left and rightfinal transmission devices 40 for transmitting the power transmitted tothe rear wheel differential device 38 to left and right rear wheel axles39. The traveling drive shaft 34, the HST 35, the mechanicaltransmission device 37, the bevel pinion shaft 36, and the rear wheeldifferential device 38 are disposed in front of the engine 7, and thefinal transmission devices 40 are arranged so as to extend from thesides of the rear wheel differential device 38 to the sides of the frontpart of the engine 7.

The traveling drive shaft 34 is arranged in the front-rear direction infront of the engine 7, and the rear end thereof is connected to aflywheel 42 that is connected to the output shaft 23 of the engine 7.

In the HST 35 as shown in FIGS. 8 and 30, an input shaft 44 forinputting the power from the engine 7, and an output shaft 45 foroutputting power to the rear wheel differential device 38 are providedin parallel fashion on the left and right inside a casing 43, and thecasing 43 accommodates a hydraulic pump 46 provided to the input shaft44, and a hydraulic motor 47 provided to the output shaft 45. The HST 35is a transmission in which the hydraulic motor 47 is driven by pressureoil that is sent from the hydraulic pump 46 driven by the input shaft44, and power is outputted from the output shaft 45 driven by thehydraulic motor 47.

The casing 43 is composed of a main body 48 in which the rear side isopen, and a cover 49 for covering the opening on the rear side of themain body 48, and the input shaft 44 and the output shaft 45 protrude tothe rear from the cover 49.

The input shaft 44 of the HST 35 is disposed coaxially with thetraveling drive shaft 34 and in front of the traveling drive shaft 34,and is coupled and connected to the traveling drive shaft 34 by acoupling.

The hydraulic pump 46 is composed of a variable displacement pump inwhich the angle of a swash plate can be varied by a swash plate controlactuator 50, and by varying the angle of the swash plate, the flow ofpressure oil discharged to the hydraulic motor 47 is varied, and therotational speed (wheel speed) of the output shaft 45 can be varied. Thehydraulic pump 46 can change the direction of the flow of pressure oildischarged to the hydraulic motor 47 and switch the rotation directionof the output shaft 45 to positive rotation (forward rotation) ornegative rotation (reverse rotation).

The swash plate control actuator 50 is controlled by a forward-reverseswitching means 51 that is composed of a pilot operation switching servovalve operated by a pilot pressure. When the pilot pressure rises in aforward travel port 52 of the forward-reverse switching means 51, theswash plate of the forward-reverse switching means 51 is controlled sothat the output shaft 45 rotates positively. When the pilot pressurerises in a reverse travel port 53, the swash plate of the hydraulic pump46 is controlled so that the output shaft 45 rotates negatively. Theflow rate of pressure oil discharged from the hydraulic pump 46 iscontrolled by the amount of pressure that occurs in the forward travelport 52 or the reverse travel port 53, and the rotational speed of theoutput shaft 45 is controlled.

The hydraulic motor 47 is composed of a variable displacement pump, theangle of the swash plate can be changed between two levels by a high-lowswitching actuator 54, and the rotational power outputted from theoutput shaft 45 can be switched between a high speed and a low speed byvarying the swash plate angle.

The bevel pinion shaft 36 is arranged in parallel fashion below and tothe left of the portion of the output shaft 45 of the HST 35 thatprotrudes to the rear from the cover 49. The bevel pinion shaft 36extends further to the rear than the rear end of the output shaft 45 ofthe HST 35, and a bevel gear part is formed on the rear end of the bevelpinion shaft 36.

The mechanical transmission device 37 in the present embodiment is aspeed reduction mechanism composed of a gear transmission mechanismcomposed of a drive-side gear 56 fitted so as to be able to integrallyrotate with the portion of the output shaft 45 of the HST 35 thatprotrudes to the rear from the cover 49, and a driven-side gear 57 thatmeshes with the drive-side gear 56 and is fitted so as to be able tointegrally rotate with the front end of the bevel pinion shaft 36.

The mechanical transmission device 37 may be an acceleration mechanism(speed change mechanism) or a same-speed mechanism, and may be atransmission that performs coupling and other power transmission.

The rear wheel differential device 38 is disposed behind the bevelpinion shaft 36 and in front of the left side of the engine 7, anddifferential output shafts 58 protrude to the left and right.

The rear wheel axles 39 are provided to the rear of the differentialoutput shafts 58 of the rear wheel differential device 38 so as tooverlap the engine 7 as viewed from the side, and the rear wheels 5 areattached and fixed to the outer ends of the left and right rear wheelaxles 39.

The final transmission devices 40 are speed reduction mechanismscomposed of gear transmission mechanisms that have drive-side gears 59fitted so as to be able to integrally rotate with the outer ends in theleft-right direction of the differential output shafts 58, anddriven-side gears 60 that are fitted so as to be able to integrallyrotate with the rear wheel axles 39.

The final transmission devices 40 may also be acceleration mechanisms(speed change mechanisms) or same-speed mechanisms.

In the traveling system power transmission mechanism 8 configured asdescribed above, the power outputted to the front from the engine 7 isredirected by the HST 35 and transmitted to the rear, the power istransmitted to the left and right sides by the rear wheel differentialdevice 38 in front of the engine 7 and transmitted to the rear by thefinal transmission devices 40 so as to reach the rear wheel axles 39,and the traveling system power transmission mechanism 8 is thus madecompact in the front-rear direction.

A housing 61 for accommodating the flywheel 42, the rear wheeldifferential device 38, and other components is connected and fixed tothe front side of the engine 7. A transmission case 62 for accommodatingthe mechanical transmission device 37 and other components is connectedand fixed to the front side of the housing 61. The housing 43 (cover 49)of the HST 35 is connected and fixed to the front side of thetransmission case 62. The rear wheel differential device 38, themechanical transmission device 37, the HST 35, and other components arethus attached to, and integrated with, the engine 7; the housing 61, thetransmission case 62, and the housing 43 are positioned between the leftand right side walls 19 of the main frame 9; and the forward side of theengine positioning part 11 between the left and right side walls 19 ofthe main frame 9 forms a traveling power transmission system positioningpart 63.

Final transmission cases 67 for accommodating the final transmissiondevices 40 are fixed to the left and right sides of the housing 61. Therear wheel axles 39 are supported by the final transmission cases 67,and the final transmission cases 67 are attached and fixed to the mainframe 9.

The inside ends in the left-right direction of the front parts of theleft and right final transmission cases 67 are bolted to the sides ofthe housing 61, and the rear sides of the left and right finaltransmission cases 67 are bolted to the upper sides of the side walls 19of the main frame 9.

Case fitting parts 64 composed of cut-out parts that open downward so asto fit onto the upper parts of the final transmission cases 67 fromabove are formed in the lower rear parts of the left and right sidewalls 19 of the main frame 9. The final transmission cases 67 are boltedto the main frame side walls 19 around the case fitting parts 64.

The front part of the engine 7 is supported by the main frame 9 via thehousing 61 and the final transmission cases 67. The rear part of theengine 7 is supported by tabbed parts 65 formed in the rear wall 21 ofthe main frame 9, and connecting plates 66 for connecting the lower sidesurfaces of the engine 7.

In the configuration described above, since the housing 61, thetransmission case 62, the housing 43 of the HST 35, and the finaltransmission cases 67 are attached to, and integrated (unitized) with,the engine 7 (since the rear wheel differential device 38, themechanical transmission device 37, the HST 35, the final transmissiondevices 40, and the rear wheel axles 39 are attached to, and integratedwith, the engine 7. As a result, after these components are assembled,the machine frame 6 can be assembled with the assembly from above theengine 7 and other components, and assembly with respect to the machineframe 6 is facilitated.

A configuration may be adopted in which the housing 61, the transmissioncase 62, the HST 35, and the final speed change cases are combined,after which the machine frame 6 is assembled with the assembly fromabove, the engine 7 is then inserted between the left and right sidewalls 19 from the top side of the upper wall 18 of the main frame 9, andthe engine 7 is then attached and fixed to the housing 61 and the rearwall 21 of the main frame 9.

In this case, the cut-out opening 24 formed in the upper wall 18 of themain frame 9 is formed so as to be large enough to allow the engine 7 tobe inserted between the left and right side walls 19 from above.

The rear wheel differential device 38 is provided in front of the engine7, and the rear wheel axles 39 for receiving the power from the rearwheel differential device 38 and rotating the rear wheels 5 are providedto the rear of the differential output shafts 58 so as to overlap theengine 7 as viewed from the side, whereby the swiveling work machine 1can be made compact in the front-rear direction.

In other words, by providing the rear wheel differential device 38 infront of the engine 7, the engine 7 can be separated to the rear fromthe swivel axis X (center of the rotation bearing 16) of the rotatingbody 3, and a wide space can be obtained in the step 215 describedhereinafter.

The engine 7 is positioned behind the rear wheel axles 39 when the rearwheel axles 39 are provided in the same axis as the differential outputshafts 58 of the rear wheel differential device 38, and when work isperformed with the rotating body 3 facing the rear, the distance fromthe rear wheel axles 39 to the work position behind the engine 7increases, and work properties are poor in comparison to the presentembodiment. Therefore, the work properties when the rotating body 3 isfacing the rear are improved by providing the rear wheel axles 39 to therear of the differential output shafts 58 so as to overlap the engine 7as viewed from the side according to the present embodiment.

In the positioning of the rear wheel differential device 38 in front ofthe engine 7, the rear wheel differential device 38 is positioned awayfrom the flywheel 42 in the left and right directions, and the rearwheel differential device 38 can therefore be positioned as close aspossible to the engine 7. The distance between the differential outputshafts 58 and the rear wheel axles 39 is thereby reduced, and the finaltransmission devices 40 and final transmission cases 67 can be madecompact.

The left-right width of the swiveling work machine increases when theleft and right side frame parts of the machine frame are composed ofangled pipe, and although the final transmission cases 67 are attachedand fixed to the outer sides of the angled pipe in the left-rightdirection, and the left-right width of the swiveling work machine doesnot increase when the final transmission cases 67 are attached and fixedto the lower surfaces of the angled pipe, the height of the travelingbody 2 increases.

In contrast, in the present embodiment, the main frame 9 of the machineframe 6 is provided with the upper wall 18 and the left and right sidewalls 19 formed by sheet materials, the engine 7 is positioned betweenthe left and right side walls 19, and the final transmission cases 67are attached and fixed to the left and right side walls 19. Therefore,the swiveling work machine 1 can be made compact in the left-rightdirection, or the vertical dimensions can be reduced, and the rotatingbody 3 on top can be positioned low.

A main pump 68 composed of a double-barreled gear pump coupled andconnected to the front end of the input shaft 44 and driven by the inputshaft 44 of the HST 35 is attached to the front side of the HST 35, andoperating oil is fed from the main pump 68 to various types of actuatorsprovided to the swiveling work machine 1.

In the present embodiment, an oil pan 69 provided to the bottom end ofthe engine 7 is used as an operating oil tank for storing operating oilfor hydraulic devices.

The traveling system power transmission mechanism 8 is provided with afoot brake means 70 (travel brake) for restricting the travel powertransmitted from the HST 35 to the rear wheel differential device 38,and a drive-wheel brake means 71 for maintaining the power transmissionsystem between the HST 35 and the rear wheel differential device 38 in astopped state. The brake means 70, 71 are disposed behind the drive-sidegear 56 of the mechanical transmission device 37.

The foot brake means 70 is accommodated in the transmission case 62, andhas a brake case 72 fixed to the transmission case 62, a brake disk 73fitted onto the rear end of the output shaft 45 of the HST 35 so as tobe able to integrally rotate, a plate 74 provided to the brake case 72,and a piston 75 for pressing the brake disk 73 and the plate 74together. The pressure oil inside a master cylinder 372 presses on thepiston 75 through the pressing operation of a brake pedal 364 providedto the rotating body 3, whereby the piston 75 moves, and the brake disk73 and plate 74 are pressed together, and the output shaft 45 of the HST35 is thereby restricted.

The drive-wheel brake means 71 is disposed behind the foot brake means70, and has a drive-wheel brake case 76 accommodated in the housing 61and fixed to the housing 61, and a piston 77 accommodated in thedrive-wheel brake case 76.

The brake case 72 is open to the rear, the drive-wheel brake case 76 isopen to the front, and the brake case 72 and drive-wheel brake case 76are communicated with each other.

A spring 78 for pushing on the piston 77 and pushing the brake disk 73and plate 74 together when the engine 7 is stopped is accommodated inthe drive-wheel brake case 76. Through the starting of the engine 7, thepressure oil from a charge pump 79 (see FIG. 30) driven by the engine 7acts on the piston 77 and moves the piston 77 against the urging forceof the spring 78, and the pressing together of the brake disk 73 and theplate 74 is released.

A differential locking device 80 is provided to the left of the rearwheel differential device 38. As shown in FIG. 8, the differentiallocking device 80 is a hydraulic differential locking device 80 in whicha differential locking cylinder 81 that rotates integrally with theleft-side differential output shaft 58 is moved by oil pressure towardthe rear wheel differential device 38 against a return spring, andlocking teeth formed in the differential locking cylinder 81 mesh withlocking teeth provided to the rear wheel differential device 38, wherebydifferential action of the rear wheel differential device 38 isprevented, and differential locking occurs.

An open part 83 is formed in the upper surface of the upper wall 18 atthe front of the main frame 9, and a bearing attachment plate 84composed of a thick plate material is fixed to the upper surface of theupper wall 18 so as to block the open part 83.

The rotation bearing 16 is disposed on the bearing attachment plate 84,and the outer race 85 of the rotation bearing 16 is bolted and attachedto the bearing attachment plate 84.

The rotation bearing 16 is disposed in the substantial center betweenthe front and rear wheels 4, 5, the axis of the rotation bearing 16 isdesignated as the swivel axis X, and the upper surface of the bearingattachment plate 84 on the upper surface of the upper wall 18 at thefront of the main frame 9 is designated as a bearing positioning part86.

An internal gear 89 is formed in the internal peripheral side of theinner race 87 of the rotation bearing 16, and a pinion 88 meshes withthe internal gear 89. The pinion 88 is fixed to the output shaft of aswivel motor 15 that is composed of a hydraulic motor fixed to the mainframe 9, and the inner race 87 of the rotation bearing 16 can berotationally driven about the swivel axis X by the swivel motor 15.

A swivel joint 14 is disposed in the same axis as the swivel axis X atthe front part between the left and right side walls 19 of the mainframe 9, and pressure oil is circulated to the traveling body 2 or therotating body 3 via the swivel joint 14.

As shown in FIGS. 9 through 15, the front frame 10 of the machine frame6 is composed of a plate material. In other words, the front frame 10 isprimarily composed of an upper wall 91, left and right side walls 92that extend downward from the left and right edges of the upper wall 91,and a connecting plate 93 for connecting the front parts of the left andright side walls 92 to each other, and the front frame 10 is formed sothat the rear part thereof opens downward.

The upper wall of the machine frame 6 is formed by the upper wall 18 ofthe main frame 9 and the upper wall 91 of the front frame 10, and theupper wall of the machine frame 6 is formed by the left and right sidewalls 19 of the main frame 9 and the left and right side walls 92 of thefront frame 10.

The front frame 10 is formed so that the left-right width thereof isless than that of the main frame 9, and front-wheel positioning spaces94 for positioning the front wheels 4 are formed in front of the mainframe 9 on the left and right sides of the front frame 10.

The dimension to which the left and right side walls 92 extend downwardfrom the upper wall 91 is less on the front side than on the rear side,the left and right side walls 92 are formed so that the vertical widthon the front sides thereof is less than on the rear sides thereof, and apositioning space for a steering cylinder 97 composed of a front-wheelaxle case 96 and a hydraulic cylinder, and other components is formedbelow the front part of the front frame 10.

The connecting plate 93 is provided with a horizontally orientedhorizontal wall part 98 for connecting the lower ends of the front partsof the left and right side walls 92 to each other, and a tilted wallpart 99 that extends in a tilted direction that moves downward towardsthe rear from the rear end of the horizontal wall part 98 and connectsthe middle parts in the front-rear direction of the left and right sidewalls 92 to each other.

A fuel tank 17 for storing the fuel for the engine 7 is provided to therear part between the left and right side walls 92 of the front frame10.

The fuel tank 17 is inserted between the left and right side walls 92from below and attached and fixed to the front frame 10. The frontsurface of the fuel tank 17 is positioned in contact with the tiltedwall part 99 of the connecting plate 93, and the lower rear end of thefuel tank 17 protrudes toward the main frame 9 via a cut-out part formedat the lower end of the front wall of the main frame 9.

A passage hole that passes through a fill opening 100 of the fuel tank17 is formed in the upper wall 91 of the front frame 10, and the lowersurface of the fuel tank 17 is covered by a cover (not shown) mounted tothe lower surface of the front frame 10 after the fuel tank 17 ismounted.

The front-wheel axle case 96 for steerably linking the left and rightfront wheels 4 is disposed in a left-right orientation on the lowersurface of the horizontal wall part 98 of the connecting plate 93 of thefront frame 10. Front wheel bearings 101 attached and fixed to the lowersurface of the horizontal wall part 98 of the connecting plate 93 areprovided on the front and rear sides of the left-right center part ofthe front-wheel axle case 96, and the front-wheel axle case 96 issupported by the front and rear front wheel bearings 101 via center pins102 so as to be able to pivot about a front-rear-directed axis.

Gear cases 103 are provided on the left and right sides of thefront-wheel axle case 96, and the front wheels 4 are supported by theleft and right gear cases 103 so as to be able to steer.

The steering cylinder 97 for steering the front wheels 4 is positionedin the left-right direction in front of the front-wheel axle case 96 andattached and fixed to the front-wheel axle case 96. The steeringcylinder 97 is provided with piston rods that protrude from the left andright sides of a cylinder tube, the left and right piston rods arecoupled and connected to the front wheels 4 on the same side in theleft-right direction, and the steering cylinder 97 is controlled by apower steering controller 367 provided to the rotating body 3.

Since the front wheels 4 are the steered wheels, a large space isrequired to accommodate the front wheels 4, and the left-right width ofthe swiveling work machine 1 is large when the front frame 10 is formedso as to have the same width as the main frame 9 in the left-rightdirection. However, in the present embodiment, the left-right width ofthe front frame 10 is less than that of the main frame 9, and thefront-wheel positioning spaces 94 are formed for positioning the frontwheels 4 in front of the main frame 9 and on the left and right sides ofthe front frame 10, and the left-right width of the swiveling workmachine 1 can therefore be prevented from increasing.

The front wheel drive system 33 for transmitting power to the frontwheels 4 is provided with a front wheel power takeoff shaft 104 thatprotrudes forward from the transmission case 62 and is connected to thedriven-side gear 57 of the mechanical transmission device 37; a frontwheel differential device 105 provided in the front-wheel axle case 96;a bevel pinion shaft 106 for inputting power to the front wheeldifferential device 105; a transmission shaft 107 for coupling andconnecting the bevel pinion shaft 106 and the front wheel power takeoffshaft 104 to each other; and a final speed reduction mechanism(transmission mechanism) (not shown) for transmitting power from thedifferential output shaft 108 of the front wheel differential device 105to a front wheel drive shaft 109 for driving the front wheels 4.

Actuation bodies 111 that pivot integrally with the front-wheel axlecase 96 are provided to the front-wheel axle case 96, and a pivotlocking mechanism 112 for restricting the pivoting of the front-wheelaxle case 96 by restricting the pivoting of the actuation bodies 111 isprovided to the machine frame 6 (front frame 10).

The actuation bodies 111 are disposed in a pair front and behind thecenter in the left-right direction of the front-wheel axle case 96, andeach actuation body 111 is bolted to an attachment part 113 provided tothe front-wheel axle case 96.

The front and rear actuation bodies 111 pass through the horizontal wallpart 98 of the connecting plate 93 and protrude upward, and a fittingpart 114 that is open upward and to the front and rear is formed in theupper parts of the actuation bodies 111.

The pivot locking mechanism 112 is provided with a locking cylinder 115disposed between the upper parts of the front and rear actuation bodies111, and a switch valve 118 for switching two chambers 124A, 124Bpartitioned by a piston 117 inside a cylinder tube 116 of the lockingcylinder 115 between a communicated state and a closed state(non-communicated state).

The locking cylinder 115 is disposed horizontally so that the axisinside a positioning opening 119 formed in the upper wall 91 of thefront frame 10 coincides with the left-right direction. The lockingcylinder 115 is primarily composed of the cylinder tube 116 filled witha fluid (oil in the present embodiment), the piston 117 accommodated inthe cylinder tube 116 so as to be able to move in the left-rightdirection, and a pair of left and right piston rods 120 fixed to theleft and right sides of the piston 117 that protrude outward to the leftand right from the cylinder tube 116.

The left and right piston rods 120 are attached to and supported bysupport plates 121 on the same sides in the left-right direction.

The left and right support plates 121 are provided upright on thehorizontal wall part 98 of the connecting plate 93 of the front frame10, and radial attachment grooves 122 are formed above and on the leftand right sides of the center part of the upper part in the front-reardirection.

Attachment bolts 123 composed of headed bolts are threaded in theleft-right direction on the outer ends of the left and right piston rods120, and the left and right piston rods 120 are attached and fixedhorizontally in the left-right direction on the side of the front frame10 (machine frame 6) by inserting and fitting the shaft portions of theattachment bolts 123 from above the attachment grooves 122 of thesupport plates 121, and then tightening the attachment bolts 123.

A fitted part 126 for coupling and connecting the cylinder tube 116 tothe actuation bodies 111 by being fitted onto the fitting parts 114 ofthe actuation bodies 111 from above is provided on the front and rearsides of the center part of the cylinder tube 116 in the left-rightdirection.

The fitted part 126 is composed of a pin having a central axis in thefront-rear direction, and is fitted with the fitting part 114 of theactuation bodies 111 at the same time that the piston rods 120 areattached.

The switch valve 118 is composed of a two-port two-position switch valve118, wherein one port is communicated via a hose or the like with onechamber 124A in the cylinder tube 116, the other port is communicatedvia a hose or the like with the other chamber 124B in the cylinder tube116, and fluid (oil) is filled into the passage from one chamber 124A ofthe cylinder tube 116 to the other chamber 124B.

A pair of in/out ports 125A, 125B for allowing inflow and outflow offluid with respect to the two chambers 124A, 124B of the cylinder tube116 is provided to the upper surface of the cylinder tube 116.

In the pivot locking mechanism 112, the cylinder tube 116 is allowed tomove left and right, and the front-wheel axle case 96 is allowed topivot in the state in which the switch valve 118 is switched to thecommunicated state in which fluid flows from one chamber 124A of thecylinder tube 116 to the other chamber 124B. In the state in which theswitch valve 118 is switched to the non-communicated state in whichfluid does not flow from one chamber 124A of the cylinder tube 116 tothe other chamber 124B, left-right movement of the cylinder tube 116 isrestricted, and pivoting of the front-wheel axle case 96 is restricted(locked).

The locking cylinder 115 of the pivot locking mechanism 112 configuredas described above is attached by fitting the attachment bolts 123 ofthe piston rods 120 in the attachment grooves 122 of the support plates121 at the same time that the fitted part 126 of the cylinder tube 116is fitted with the fitting part 114 of the actuation bodies 111 fromabove, and then tightening the attachment bolts 123. The lockingcylinder 115 can thus be easily attached.

As assembly methods, the front-wheel axle case 96 to which the actuationbodies 111 are attached may be mounted to the front frame 10, and thenthe locking cylinder 115 may be mounted, or the locking cylinder 115 mayfirst be mounted to the front frame 10, and then the front-wheel axlecase 96 to which the actuation bodies 111 are attached may be mounted tothe front frame 10.

In the present embodiment, the cylinder tube 116 is disposedhorizontally, and the fluid in/out ports 125A, 125B provided to thecylinder tube 116 are formed on the upper surface of the cylinder tube116. Therefore, when air accumulates in the cylinder tube 116, the aircan be removed via the in/out ports 125A, 125B.

The rotating body 3 is provided with a rotation table 201 supported onthe machine frame 6 so as to be able to swivel about a verticallydirected swivel axis; a steering device 202 for the travel system, andan excavating implement 203 as a ground implement provided to the frontpart of the rotation table 201; a driver seat positioning frame 204provided to the rear part of the rotation table 201; a driver seat 205provided to the driver seat positioning frame 204; operating devices 206for the excavating implement provided on the left and right sides of thedriver seat 205; a control valve (switching valve of the operatingdevices 206) 207 and a counterweight 208 for the excavating implementthat are provided to the driver seat positioning frame 204; and a ROPS(Roll Over Protective Structure) 209. The swivel axis X coincides withan axis line orthogonal to the axis between the front and rear wheels.

As shown in FIGS. 22 and 23, the front part of the rotation table 201 isflat, the left and right sides extend to the rear further outward thanthe machine frame 6, and the rear part and the left and right side partsare formed so as to be substantially rectangular.

The rotation table 201 is also provided with a front frame 211; a rearframe 212 positioned at a distance to the rear from the front frame 211;a pair of left and right side frames 213 for connecting the front frame211 and the rear frame 212 on the left and right sides thereof; a lowerwall 214 provided between the front and rear frames 211,212 on the lowersurface of the rotation table 201; and a step 215 (footrest) provided tothe upper surface of the lower wall 214.

Masts (implement supports) 216 are provided upright on the left andright sides (left and right sides of the front frame part) on the uppersurface of the front frame 211, and the excavating implement 203 isattached to the pair of left and right masts 216.

As shown in FIGS. 1 and 16 through 21, the excavating implement 203 hasa pair of left and right booms 241 pivotally connected to the upperparts of the left and right masts 216 so as to be able to rotate about aleft-right axis; a pair of left and right arms 242 whose proximal sidesare pivotally connected to the distal ends of the left and right booms241 so as to be able to rotate about a left-right axis; a bucket 243 asan attachment tool for ground work that is provided to the distal endsof the left and right arms 242; a pair of left and right boom cylinders244 for pivoting the left and right arms 241 vertically about a pivotpoint; a pair of left and right arm cylinders 245 for pivoting the leftand right arms 242 to the front and rear about a pivot point; and asingle bucket cylinder 246 for pivoting the bucket 243.

The bucket cylinder 246, the arm cylinders 245, are composed ofhydraulic cylinders.

The proximal sides of the left and right arms 242 are connected byconnecting members 247 that are composed of pipes disposed along theleft-right direction, and one end (the piston top of the cylinder mainbody) of the bucket cylinder 246 is pivotally connected to a bracket 248so as to be able to rotate about a left-right axis, and the bracket 248is provided in the center of the connecting members 247 in theleft-right direction.

A support body 249 for supporting the bucket 243 is provided to thedistal ends of the left and right arms 242.

The 249 is composed of a plate material having a surface in theleft-right direction. The bucket 243 is supported at the front surfaceof the support body 249. Attachment brackets 250 are provided to theleft and right sides of the back surface of the support body 249, andthe distal ends of the arms 242 on the same sides in the left-rightdirection are pivotally connected to the lower parts of the left andright attachment brackets 250 so as to be able to rotate about aleft-right axis via a horizontal shaft 251.

A support shaft 252 having a central axis in the left-right direction isprovided so as to be able to rotate about the central axis, and connectsthe left and right arms 242 nearer the proximal part than the horizontalshaft 251 at the distal ends of the arms 242. One end of a first link253 is connected in the center in the left-right direction of thesupport shaft 252. A second link 254 is pivotally connected to the otherend of the first link 253 so as to be able to rotate about a left-rightaxis. The other end of the second link 254 is pivotally connected to abracket 255 so as to be able to rotate about a left-right axis, and thebracket 255 is provided in the center in the left-right direction of theback surface of the support body 249.

The other end (on the side of the distal end of the piston rod) of thebucket cylinder 246 is pivotally connected to a midportion of the firstlink 253 so as to be able to rotate about a left-right axis. Through theextension and retraction of the bucket cylinder 246, the bucket 243pivots about the horizontal shaft 251 (about a left-right axis), and thebucket 243 is capable of scooping/dumping or raking/dumping operation.

The bucket 243 is supported by the support body 249 so as to be able torotate about a rotation shaft 257 having a central axis Y perpendicularto the bucket 243 (attachment tool support surface 256) of the supportbody 249. The bucket 243 is capable of rotating 180° about the centralaxis Y of the rotation shaft 257 from a first work orientation thatallows scooping as shown in FIG. 18A, to a second work orientation thatallows raking as shown in FIG. 18B through the use of a rotation means258 provided between the bucket 243 and the support body 249.

The rotation means 258 has a cylinder tube 259 fixed to the support body249, a piston 260 accommodated in the cylinder tube 259, and therotation shaft 257 fixed to the bucket 243 and inserted into the piston260.

The cylinder tube 259 has the central axis Y of the rotation shaft 257of the bucket 243 as the central axis thereof, and is inserted in thesupport body 249 so as to protrude to the front and rear of the supportbody 249. The cylinder tube 259 is bolted to the support body 249, thefront surface thereof is open, and in/out ports 261A, 261B for pressureoil are formed in the front and rear thereof.

The rotation shaft 257 is inserted from the front surface of thecylinder tube 259. The rotation shaft 257 is primarily composed of afront attachment part 262 for blocking the opening at the front surfaceof the cylinder tube 259, and a midportion-to-rear shaft part 263 formedso as to have a smaller diameter than the attachment part 262. In thisrotation shaft 257, the attachment part 262 and the rear end of theshaft part 263 are supported by the cylinder tube 259 so as to be ableto rotate about a central axis, and the rear end of the shaft part 263is attached by a bolt to the cylinder tube 259 so as to be incapable ofmoving in the central axis direction.

An attachment plate 264 is bolted to the attachment part 262 of therotation shaft 257, and the attachment plate 264 is bolted to the backwall 265 of the bucket 243, whereby the rotation shaft 257 is attachedand fixed so as to be able to rotate integrally with the bucket 243.

The piston 260 is formed in a cylindrical shape, fitted into thecylinder tube 259 so as to be able to move in the central axis directionbut not rotate about the central axis, and is fitted onto the shaft part263 of the rotation shaft 257 so as to be able to move in the centralaxis direction but not rotate in relative fashion about the centralaxis.

Screws 266, 267 for meshing with each other and converting linearmovement of the piston 260 into rotation of the rotation shaft 257 areformed on the external peripheral side of the shaft part 263 of therotation shaft 257, and the internal peripheral side of the piston 260.Pressure oil is fed into the cylinder tube 259 from one or the other ofthe in/out ports 261A, 261B of the cylinder tube 259, whereby the piston260 moves linearly in the central axis direction, and the rotation shaft257 rotates about the central axis through the meshing of the screw 267on the internal peripheral side of the piston 260, and the screw 266 onthe external peripheral side of the shaft part 263 of the rotation shaft257.

The piston 260 moves from one end to the other end, and the bucket 243can thereby rotate by 180°.

In the example shown in the drawings, the piston 260 is set so that thebucket 243 is in the first work orientation when the piston 260 ispositioned at a slight distance (about 3 mm) from the stroke end at thefront end (one end), and the bucket 243 is in the second workorientation when the piston 260 is positioned at a slight distance(about 3 mm) from the stroke end at the rear end (other end).

A rotation restriction means 268 is provided to the excavating implement203. In the first work orientation, the rotation restriction means 268restricts rotation (first-direction rotation of the bucket 243) of thebucket 243 in the direction (indicated by the arrow A in FIG. 21) ofrotation from the second work orientation to the first work orientation,and allows the bucket 243 to rotate in the direction opposite from thefirst-direction rotation A. In the second work orientation, the rotationrestriction means 268 restricts rotation (second-direction rotation ofthe bucket 243) of the bucket 243 in the direction (indicated by thearrow B in FIG. 21) of rotation from the first work orientation to thesecond work orientation, and allows the bucket 243 to rotate in thedirection opposite from the second-direction rotation B.

The rotation restriction means 268 is provided with locking parts 269that rotate integrally with the bucket 243, and first lock-receivingparts 270 and second lock-receiving part 271 provided to the supportbody 249 that lock the locking parts 269.

The locking parts 269 are composed of pins having a central axis in theleft-right direction, and are fixed to brackets 272 that are fixed tothe back wall 265 of the bucket 243.

The first lock-receiving parts 270 and the second lock-receiving parts271 are hook shaped and fixed to the front surface of the support body249. The first lock-receiving parts 270 are open in the direction of thesecond-direction rotation B of the bucket 243, and lock the lockingparts 269 in the first work orientation so as to restrict thefirst-direction rotation A of the bucket 243 and allow thesecond-direction rotation B of the bucket 243. The second lock-receivingparts 271 are open in the direction of the first-direction rotation A ofthe bucket 243, and lock the locking parts 269 in the second workorientation so as to restrict the second-direction rotation B of thebucket 243 and allow the first-direction rotation A of the bucket 243.

The locking parts 269, the first lock-receiving parts 270, and thesecond lock-receiving parts 271 are formed so as to receive the loadthat acts on the bucket 243 during excavation work, and a pluralitythereof (four each in the present embodiment) is formed on the peripheryof the rotation means 258. The share of the load exerted on the rotationshaft 257 from the bucket 243 during excavation work can thereby bereduced.

An orientation retention means 273 for retaining the bucket 243 in thefirst work orientation and the second work orientation is provided tothe excavating implement 203.

The orientation retention means 273 is disposed on the back surface ofthe support body 249. The orientation retention means is supported so asto be able to move along a bucket support surface 256 of the supportbody 249, and the distal end thereof has an engaging member 276 capableof protruding and retracting from the external peripheral edge of thesupport body 249, and engagement-receiving parts 277 provided in twolocations 180° apart about the rotation shaft 257 toward the attachmenttool that engage with the engaging member 276 protruding from theexternal periphery of the support body 249 and restrict the rotation ofthe bucket 243 in the first and second work orientations.

The engaging member 276 is composed of a pin tapered at the distal endthereof and fixed to a bracket 279 in which a guide cylinder 278 forguiding the engaging member 276 to allow movement thereof in theprotrusion and retraction direction is fixed to the back surface of thesupport body 249, and the engaging member 276 is passed through thebracket 279 and inserted through the guide cylinder 278.

The engagement-receiving parts 277 are formed in a cylindrical shapethat is engaged by the insertion of the distal end of the engagingmember 276, and are formed in a tapered shape in which the internalperipheral side matches the tapered shape of the distal end of theengaging member 276.

The engagement-receiving parts 277 are fixed to attachment members 280that are attached and fixed to the back wall 265 of the bucket 243.

A release lever 281 for releasing the engaging member 276 from theengagement-receiving parts 277 and releasing the engagement thereof isprovided beside the base part of the engaging member 276.

The release lever 281 is formed in a curved V shape, and the curvedportion thereof is attached to a stepped attachment shaft 282 fixed tothe support body 249 so as to allow rotation about a central axisparallel to the central axis of the rotation shaft 257.

An engaging block 283 attached so as to be able to rotate about an axisparallel to the rotational axis of the release lever 281 is provided toone end of the release lever 281.

The release lever 281 is subjected to rotation resistance by the urgingforce of a spring member 285 composed of a compression coil spring thatis installed between the release lever 281 and a spring bearing 284 thatis fitted onto the end part of the attachment shaft 282.

One end of the release lever 281, and the proximal end of the engagingmember 276 are coupled and connected by a coupling member 286.

One end of the coupling member 286 is pivotally connected to theproximal end of the engaging member 276, and the other end of thecoupling member 286 is formed in a rod shape. The rod part 287 isinserted through the engaging block 283 at one end of the release lever281, a male screw 288 is formed at the end part of the rod part 287, anda nut 289 is threaded thereon.

A spring member 291 composed of a compression coil spring is disposed soas to fit over the rod part 287 between the engaging block 283 and aspring bearing step 290 provided to one end of the coupling member 286.

The support body 249 is provided with a contacting wall 292 with whichone end of the release lever 281 comes in contact so as to restrictrotation (counterclockwise rotation of the release lever 281 in FIG.20B) of the release lever 281 due to the urging force of the springmember 291 fitted over the rod part 287 when the engaging member 276 isengaged with the engagement-receiving parts 277. When the engagingmember 276 is engaged with the engagement-receiving parts 277, thespring member 291 fitted over the rod part 287 urges the engaging member276 toward engaging with the engagement-receiving parts 277.

When the engaging member 276 is engaged with the engagement-receivingparts 277, the other end of the release lever 281 is rotated clockwisein FIG. 20B, whereby the engaging block 283 comes in contact with thenut 289 and pulls the coupling member 286. The engaging member 276 isthereby pulled in the release direction, the engagement of the engagingmember 276 with the engagement-receiving parts 277 is released, and thebucket 243 is allowed to rotate.

The support body 249 is provided with a stopper 293 for restrictingrotation of the release lever 281 in the direction in which the engagingmember 276 is released from the engagement-receiving parts 277.

The release lever 281 is coupled and connected to a remove operatinglever provided in the vicinity of the driver seat 205 via a push-pullcable or other coupling member 294. The release lever 281 is remotelyoperated from the driver seat 205 by a remote operating means composedof the remote operating lever, the coupling member 294, and othercomponents, or is operated by a manual lever provided to the supportbody 249.

When a manual lever for operating the release lever 281 is provided tothe support body 249, the manual lever can be operated from the rotationtable 201 by raising the booms 241 and pivoting the arms 242 to the rearto fold the excavating implement 203.

In the excavating implement 203 of the present embodiment configured asdescribed above, there is minimal load on the rotation shaft 257 duringexcavation, and the rotation shaft 257 can therefore be narrow, and thecylinder tube 259 (rotation means 258) can be small sized.

Cost increases when the rotation means 258 is composed of a motor.However, in the bucket 243 of the present embodiment, it is sufficientinsofar as the bucket 243 can be changed to the two positions of thefirst work orientation and the second work orientation, and the rotationmeans 258 is composed of the cylinder tube 259, the piston 260, and therotation shaft 257, whereby the structure can be simplified, and therotation means 258 can be formed at low cost.

The limitation of manufacturing the leads of the screws 266, 267 can beeliminated by making the rotation shaft 257 into a cast article composedof FC or another material.

In the rotating body 3, the lower wall 214 of the rotation table 201 ismounted on the inner race 87 of the rotation bearing 16 and bolted, therotation table 201 is supported by the rotation bearing 16 so as to beable to swivel about the swivel axis X on the traveling body 2, and therotating body 3 in the present embodiment is capable of swivelingthrough the full range to the left and right.

In the traveling body 2 as shown in FIG. 1, the engine 7 is positionedin the rear part so that the rotation table 201 is positioned lower evenwhen the engine 7 is mounted, and the traveling system powertransmission mechanism 8 is positioned further forward than the engine7. The vertical dimension of the portion of the traveling body 2 thatfaces the rotation table 201 is thereby reduced.

In the rotating body 3 as shown in FIG. 1, the upper surface of the step215 of the rotation table 201 is provided on the traveling body 2 so asto be lower than the upper surface of the engine 7 in the traveling body2. The vehicle height is thereby minimized while the height of theoperating space of the rotating body 3 is maintained, and the swivelingwork machine 1 as a whole can be made compact in the vertical direction.The center of gravity of the swiveling work machine 1 is maintained in alow position, whereby stability is enhanced, and the burden on theoperator when entering and exiting the rotating body 3 is reduced.

The swiveling work machine 1 is made compact in the vertical directioneven when the rotating body 3 is mounted on the traveling body 2 in astate in which the upper surface of the step 215 is slightly higher thanthe upper surface of the engine 7, and by providing the rotating body 3on the traveling body 2 in a state in which at least the upper surfaceof the rotation bearing 16 provided to the rotation table 201 is lowerthan the upper surface of the engine 7, the stability and verticalcompactness of the entire swiveling work machine 1 can be enhanced.

When the rotating body 3 is in the forward orientation, thecounterweight 208 and the rear part of the driver seat positioning frame204 are positioned above the engine 7 provided to the traveling body 2.

The distance L1 from the rotation axis X to the rear end of the rotatingbody 3 is thereby substantially within the distance L2 from the rotationaxis X to the rear end of the rear wheels. Collision with an obstacle tothe rear is thereby prevented even when the rotating body 3 is rotated.

As shown in FIGS. 24 and 25, the driver seat positioning frame 204 isprovided with a support frame 321 fixed to the rotation table 201, amounting table 322 attached to the support frame for mounting the driverseat 205 so that the driver seat 205 can be pivoted and tilted forward,and a weight attachment frame 323 for attaching the counterweight 208.

The support frame 321 extends across a pair of left and right connectingportions in which the side frames 213 are connected to the rear frame212 of the rotation table 201. The support frame 321 is formed in abracket shape and has a pair of left and right diagonal parts 324 thatextend upward and to the rear of the rotation table 201 from theconnecting portions, and connecting parts 225 for connecting the rearend parts of the pair of left and right diagonal parts 324, and themounting table 322 is provided at the front of the connecting parts 225and between the pair of left and right diagonal parts 324.

The mounting table 322 is provided with a pair of left and right sidewalls 326 provided along the pair of left and right diagonal parts 324of the support frame 321; a front wall 327 provided upright from therotation table 201 so as to connect the front edges of the pair of leftand right side walls 326; an upper wall 328 that connects the pair ofleft and right side walls 326 and the edge of the upper end of the frontwall 327 and extends to the area below the connecting part 325 of thesupport frame 321; and a seat table 329 provided to the upper surface ofthe upper wall 328 to support the driver seat 205.

The seat table 329 is composed of a pair of left and right legs 330 thatextend along the edges of the upper ends of the pair of left and rightside walls 326; and a flat plate part 331 that connects the upper endparts of the pair of left and right legs 330 and extends toward thefront of the rotation table 201. As shown in FIG. 22, the flat platepart 331 is provided with an opening 332 in the position opposite theupper wall 328. As shown in FIG. 25, a pair of left and right supportfixtures 333 for supporting the driver seat 205 is provided in positionsfurther toward the front of the rotation table 201 than the opening 332,and a small window 333 a is opened between the support frames.

The weight attachment frame 323 is supported by the connecting part 325of the support frame 321. The weight attachment frame 323 is providedwith an upper frame part 334 for covering the connecting part 325 fromabove, a pair of left and right side frame parts 335 that extenddownward from the lower surface of the upper frame part 334, and a lowerframe part 336 that connects the lower ends of the side frame parts 335and extends to the left and right, and the upper frame part 334 isfastened via a bolt or other fastener to an attachment fixture 325 awelded to the connecting part 325 of the support frame 321, whereby theweight attachment frame 323 is attached to the support frame 321.

As shown in FIGS. 1 and 22, the counterweight 208 is connected via afastener to the lower frame part 336 of the weight attachment frame 323,and is provided with a lower weight 208 a that covers the rear part ofthe mounting table 322 and the rear parts of the diagonal parts 324 ofthe support frame 321 from below, and an upper weight 208 b connected tothe pair of left and right side frame parts 335 and the lower frame part336 of the weight attachment frame 323 by fasteners and covers the rearparts of the diagonal parts 324 of the support frame 321 and the rearparts of the connecting part 325 and mounting table 322 from the rear.The upper and lower weights 208 a, 208 b can be attached and detached asappropriate according to the work conditions or the weight of theexcavating implement 203, and can be replaced by a cover (not shown) orthe like composed of resin, for example.

As shown in FIGS. 2 and 3, the driver seat positioning frame 204 iscovered by a cover 341 provided so as to extend to the rear from belowthe driver seat 205. As shown in FIGS. 22 and 23, the cover 341 isprovided with a main cover 342 provided so as to extend to the rear ofthe driver seat 205 from below the pair of left and right operatingdevices 206, and a sub-cover 343 for covering below the driver seat 205.

The sub-cover 343 faces the front wall 327 of the mounting table 322 ata prescribed distance, the lower edge thereof makes contact with thestep 215, and both side edges face the side edge of the main cover 342,and the sub-cover 343 is provided in a state in which the upper edgecovers the front edge of the seat table 329. The sub-cover 343 isattached to the step 215, the mounting table 322, and other componentsby bolts or other fasteners, and can be attached and detached in theattachment position without removing the main cover 342.

The upper surface of the upper frame part 334 of the weight attachmentframe 323 is covered by a thick plate member 345 provided to the upperend of the attachment fixture 325 a, and angled members 346 are providedto the left and right ends of the upper surface of the thick platemember 345. Groove-shaped rear ROPS supports 347 for supporting the ROPS209 are formed at the upper ends of ascending parts of the angledmembers 346.

As shown in FIG. 23, front ROPS supports 348 are formed in a plane inthe upper ends of the pair of left and right masts 216, and the ROPS 209is supported by the pairs of left and right front ROPS supports 348 andrear ROPS supports 347 at the front and rear of the rotation table 201.

As shown in FIGS. 1 and 2, the ROPS 209 is formed by bending cylindricalsteel pipes into a U shape. The ROPS 209 is provided with left and rightfront pillars 351 that extend upward from the front ROPS supports 348;left and right rear pillars 352 that extend upward from the weightattachment frame 323; and left and right beams 353 for connecting theupper ends of the front pillars 351 and the upper ends of the rearpillars 352; and the proximal ends of the pair of left and right rearpillars 352 are connected to each other. A plurality of connecting rods354 for connecting the left and right beams 353 is provided to the ROPS209, and a canopy (not shown) is attached to the top to provide shade.

As shown in FIG. 23, a plate-shaped connecting tab 351 a is fixed to thelower ends of the pair of left and right front pillars 351 of the ROPS209. The connecting tab 351 a is fastened to the front ROPS supports 348by fasteners, and the proximal ends of the left and right rear pillars352 are supported by the rear ROPS supports 347, whereby the ROPS 209 ismounted to the rotation table 201.

The driver seat 205 is provided with a seat 355 in which the operatorcan sit, and a seat support 356 for supporting the seat 355 to allowadjustment of the seat position forward and backward, and a connectingfixture 357 connected to the support fixtures 333 of the seat table 329is provided to the front part of the seat support 356.

The connecting fixture 357 is pivotally connected to the supportfixtures 333 via a pivot pin (not shown) having a left-right axis, andthe driver seat 205 is thereby mounted so as to be able to tilt forwardabout a front pivot point on the seat table 329 of the mounting table322.

The seat support 356 is provided with a cover member 358 for coveringthe opening 332 of the seat table 329 in a state in which the driverseat 205 is mounted on the seat table 329. The opening 332 covered bythe cover member 358 can thereby be uncovered by pivoting the driverseat 205 from the mounted state on the seat table 329 to aforward-tilted state, as indicated by the double-dashed line in FIG. 23.The uncovered opening 332 is then covered by the cover member 358 bypivoting the driver seat 205 from the forward-tilted state to themounted state on the seat table 329.

The left and right legs 330 of the seat table 329 each support anoperating lever 361 provided beside the driver seat 205 via supportmembers (not shown). The operating levers 361L, 361R are operatingdevices 206 for the excavating implement. The left operating lever 361Loperates the rotation table 201 and the arms 242 of the excavatingimplement. The right operating lever 361R operates the booms 241 and thebucket 243.

A bucket rotation lever 361C for enabling the bucket 243 to be rotatedis provided behind the right operating lever 361R.

The steering device 202 of the traveling system is provided with asteering platform 362 positioned in the left-right center of the frontpart of the rotation table and between the pair of left and right masts216; a steering wheel 363 and brake pedal 364 supported by the steeringplatform 362; and a forward/reverse switching pedal (accelerator pedal)365 supported by the rotation table 201

As shown in FIG. 23, the steering platform 362 is provided with a wheelpost 366 for supporting the steering wheel 363; the power steeringcontroller 367; and a tilt device (not shown) for allowing the forwardand backward position of the steering wheel 363 to be adjusted. Thesemembers can be compactly installed on the rotation table 201 after beingcombined as a single assembly.

In the brake pedal 364 as shown in FIGS. 23 and 26, a stepping part 364a having a left-right length that is substantially the same or slightlylarger than the left-right length of the steering platform 362 isprovided behind the base part of the steering platform 362, and thebrake pedal 364 is pivotally supported by a left-right oriented supportshaft provided to the steering platform 362. The brake pedal 364 is alsourged so as to be able to return to the pre-application position afterapplication thereof is released.

As shown in FIGS. 23 and 27, the forward/reverse switching pedal 365 isprovided with an elongated pivoting body 365 a in which the midportionis supported to allow pivoting about a left-right oriented supportshaft; a front stepping part 365 b provided to the front end part of thepivoting body 365 a; and a rear stepping part 365 c provided to the rearend part; and the forward/reverse switching pedal 365 is urged so as tobe able to return to the middle position when front application or rearapplication is released.

As shown in FIGS. 22 and 23, the control valve 207 and an operatingforce relay part 371 of the steering device 202 are provided in thespace S formed by the sub-cover 343 and the front wall 327, upper wall328, and seat table 329 of the mounting table 322 below the driver seat205 mounted on the seat table.

The operating force relay part 371 is provided with the master cylinder372 and an operating tool thereof for operating the foot brake means 70,and the remote control valve (switching valve) 373 and an operating toolthereof for the HST.

As shown in FIG. 26, the master cylinder 372 is supported between thefront wall 327 and the sub-cover 343 by an attachment member 374 thatprotrudes from the rotation table 201 in a state in which thelongitudinal direction thereof is the vertical direction. The brakepedal 364 is connected to the master cylinder 372 via a plurality oflink mechanisms, rods, and the like that constitute an operating tool.According to this configuration, the piston of the master cylinder 372is pushed in by the application of the brake pedal 364, the oil pressurein the master cylinder 372 increases, the oil pressure is transmitted tothe foot brake means 70 of the traveling body 2, and braking is appliedto the rear wheels.

A brake oil tank 375 is provided beside the master cylinder 372, and anoil inflow port 375 a of the brake oil tank 375 protrudes upwardslightly from the small window 333 a of the seat table 329.

A differential locking actuation means 377 for actuating thedifferential locking device 80 provided to the traveling body 2 isprovided to the attachment member 374. The differential lockingactuation means 377 is provided with a switching valve 378 capable ofswitching the differential locking device 80 on and off, and adifferential locking lever 379 capable of operating the switching valve378. One end of the differential locking lever 379 is connected to arotating spool of the switching valve 378, and the other end extends tothe area in front of the sub-cover 343 via a guide hole (not shown)formed in the sub-cover 343. The differential locking device 80 isturned on and operated by the pressing of the other end of thedifferential locking lever 379 by an operator seated in the driver seat205. The differential locking lever 379 is urged so as to be able toreturn to the pre-application position when application thereof iswithdrawn, and the differential locking device 80 is automaticallychanged from the on state to the off state by withdrawal of application.

As shown in FIG. 27, the remote control valve 373 for the HST is formedso that a pilot pressure is created in the forward travel port 52 or thereverse travel port 53 of the forward-reverse switching means 51provided to the traveling body 2, the swash plate of the HST 35 isswitched between the forward travel state and the reverse travel state,and the travel speed of the traveling body 2 can be adjusted. The uppersurface of the remote control valve 373 is disposed in a position facingthe opening 332 of the seat table 329 so that a pivoting spool 381 forcontrolling the pilot pressure can pivot in the front-rear direction ofthe rotation table 201, and the remote control valve 373 is supported bya bracket 382 provided upright on the upper wall 328 of the mountingtable 322.

The forward/reverse switching pedal 365 is connected to the pivotingspool 381 of the remote control valve 373 via a plurality of linkmechanisms, rods, and other components that constitute an operating toolThe operating tool is provided with a cylindrical member 383 rotated bythe pivoting of the forward/reverse switching pedal 365 between theforward/reverse switching pedal 365 and the remote control valve 373.The cylindrical member 383 is provided with a first plate 384 forcoupling and connecting the forward/reverse switching pedal 365 with thepivoting spool 381 of the remote control valve 373, and a second plate385 for coupling and connecting the forward/reverse switching pedal 365with a damper device 386 that are provided so as to protrude in theradial direction.

The damper device 386 is provided with a first damper 386 a for frontapplication, and a second damper 386 b for rear application, and isdisposed behind the remote control valve 373 and above the upper wall328. The second plate 385 is connected to the first damper 386 a and thesecond damper 386 b at distal ends divided into two branches.

Through this configuration, when the front stepping part 365 b of theforward/reverse switching pedal 365 is applied, the pivoting spool 381of the remote control valve 373 is thereby pivoted in one direction viathe operating tool, and the remote control valve 373 is placed in theforward application state. When application of the front stepping part365 b is released, the forward/reverse switching pedal 365 is therebyreturned to the neutral position, but this return operation is performedgradually by the first damper 386 a.

Through application of the rear stepping part 365 c of theforward/reverse switching pedal 365, the pivoting spool 381 of theremote control valve 373 pivots in the other direction via the operatingtool, and the remote control valve 373 is placed in the reverseapplication state. When application of the rear stepping part 365 c isreleased, the forward/reverse switching pedal 365 is thereby returned tothe neutral position, but this return operation is performed graduallyby the second damper 386 b.

As shown in FIGS. 23 and 27, the control valve 207 is provided to therear of the HST remote control valve 373 and on the side of the damperdevice 386, and the upper surface of the control valve 207 faces theopening 332.

The control valve 207 controls the hydraulic actuators (the swivel motor15, the boom cylinders 244, the arm cylinders 245, the bucket cylinder246, and the rotation means 258) provided to the work machine. Thecontrol valve 207 is composed of a plurality of control valves composedof translation spool-shaped switching valves connected in the directionorthogonal to the sliding direction of the spool.

In the swiveling work machine 1 of the present embodiment, the HSTremote control valve 373 as the operating force relay part 371, theoperating tool of the remote control valve 373, the damper device 386,the master cylinder 372 for operating the foot brake means 70, theoperating tool of the master cylinder 372, the brake oil tank 375, thedifferential locking actuation means 377, and the control valve 207 areprovided in concentrated fashion in the space S below the driver seat205 as described above.

Consequently, the amount of encroachment into the driver space by thesedevices and the operating tools for these device can be minimized. Sincethe remote control valve 373, the damper device 386, and the controlvalve 207 of the HST are provided in the position opposite the opening332 of the seat table 329, inspection and maintenance of these devicescan be performed easily and at once by setting the driver seat 205 tothe forward-tilted state and unblocking the opening 332.

By setting the driver seat 205 in the forward-tilted state, the oilinflow port 375 a of the brake oil tank 375 that protrudes from thesmall window 333 a of the seat table 329 is also exposed, and oil can beinjected into the brake oil tank 375.

Furthermore, since the master cylinder 372, the brake oil tank 375, andthe differential locking actuation means 377 are provided to the rear ofthe sub-cover 343, inspection and maintenance of these devices can beperformed easily and at once by removing the sub-cover 343.

FIGS. 30 and 31 show the hydraulic oil circuit of the swiveling workmachine 1 according to the present embodiment. This hydraulic oilcircuit is divided into a traveling body side (FIG. 30) and a rotationtable side (FIG. 31) with the swivel joint 14 as the boundary.

The power of the engine 7 can drive the charge pump 79 and the main pump68 at the same time that the hydraulic pump 46 of the HST 35 is driven.

The operating oil from the main pump 68 driven by the power of theengine 7 is also fed to the control valve 207 via the swivel joint 14and sent to each actuator from the control valves V1 through V5 of thecontrol valve 207.

In the control valve 207, V1 is a swiveling control valve forcontrolling the swivel motor 15, V2 is an arm control valve forcontrolling the arm cylinders 245, V3 is a bucket rotation control valvefor controlling the rotation means 258 of the bucket 243, V4 is a boomcontrol valve for controlling the boom cylinders 244, and V5 is a bucketcontrol valve for controlling the bucket cylinder 246.

A remote control valve 393L for arms and swiveling is provided to theleft operating lever 361L of the operating devices 206. The armcylinders 245 scoop and dump via the arm control valve V1 by the forwardand backward pivoting of the left operating lever 361L. The swivel motor15 rotates left and right via the swivel control valve V2 by thepivoting of the left operating lever 361L to the left and right.

A remote control valve 393R for the bucket and the booms is provided tothe right operating lever 361R, and the bucket 243 tilts and dumps viathe attachment tool control valve V5 by forward and backward pivoting ofthe operating levers 361. By the left and right pivoting of the rightoperating lever 361R, the boom cylinders 244 raise and lower via theboom control valve V4.

Pressure oil is fed to the rotation means 258 of the bucket 243 via thebucket rotation control valve V3 through the use of a bucket rotationlever 394 provided to the rear of the left operating lever 361L, and thebucket 243 is thereby rotated.

In the present embodiment, the swivel control valve V1, the arm controlvalve V2, the arm control valve V4, and the bucket control valve V5 arecomposed of pilot-operated switching valves operated by a pilotpressure, as in the case of the remote control valves 393L, 393R, andthe bucket rotation control valve V3 is composed of the manuallyoperated switching valve 378 operated by manual operation, but thecontrol valves V1 through V5 may all be composed of pilot-operatedswitching valves.

The operating oil of the main pump 68 is fed to the steering cylinder 97through the power steering controller 367.

As shown in FIG. 30, a forward/reverse conversion means 401 is providedto pilot oil channels 395 a, 395 b for connecting the forward-reverseswitching means 51 and the remote control valve 373 for the HST. Theforward/reverse conversion means 401 detects the rotation of therotation table 201 from the forward orientation to the rearwardorientation, and the forward/reverse conversion means 401 is providedfor reversing the switching operation of the forward-reverse switchingmeans 51 by the forward/reverse switching pedal 365.

As shown in FIGS. 28 and 30, the forward/reverse conversion means 401 isprovided with a four-port three-position switch valve 402 capable ofswitching the pilot oil channels 395 a, 395 b between theforward-reverse switching means 51 and the remote control valve 373 forthe HST and feeding the pressure oil from the remote control valve 373to the forward-reverse switching means 51; and a detection mechanism 403for detecting the rotation state of the rotation table 201 and switchinga rotation spool 402 a of the switch valve 402 between three positions.

As shown in FIGS. 28 and 29, the switch valve 402 is formed by a rotaryvalve having the rotation spool 402 a, and is provided below the upperwall 18 of the main frame 9 of the traveling body 2. An operating tab404 that protrudes in the radial direction from a rotation shaft isprovided to the upper end of the rotation spool 402 a so as to protrudefurther upward than the upper wall 18, and a pin 405 is provided inprotruding fashion to the distal end of the operating tab 404.

In the switch valve 402, when the rotation spool 402 a is placed inposition A (forward connection state) as shown in FIG. 30, the remotecontrol valve 373 and the forward-reverse switching means 51 areconnected in a forward connection state, the pressure oil from a forwardtravel port 373 a of the remote control valve 373 is fed to the forwardtravel port 52 of the forward-reverse switching means 51, and thepressure oil from the reverse travel port 373 b of the remote controlvalve 373 is fed to the reverse travel port 53 of the forward-reverseswitching means 51. Accordingly, the traveling body 2 travels forwardwhen the front stepping part 365 b of the forward/reverse switchingpedal 365 is applied, and the traveling body 2 travels in reverse whenthe rear stepping part 365 c of the forward/reverse switching pedal 365is applied.

When the rotation spool 402 a of the switch valve 402 is placed inposition B (neutral state), the supply of pressure oil from the remotecontrol valve 373 to the forward-reverse switching means 51 isinterrupted, whereby the traveling body 2 can no longer travel byoperation of the forward/reverse switching pedal 365.

When the rotation spool 402 a of the switch valve 402 is placed inposition C (reverse connection state), the remote control valve 373 andthe forward-reverse switching means 51 are connected in a reverseconnection state, the pressure oil from the forward travel port 373 a ofthe remote control valve 373 is fed to the reverse travel port 53 of theforward-reverse switching means 51, and the pressure oil from thereverse travel port 373 b of the remote control valve 373 is fed to theforward travel port 52 of the forward-reverse switching means 51.Accordingly, the traveling body 2 travels in reverse when the frontstepping part 365 b of the forward/reverse switching pedal 365 isapplied, and the traveling body 2 travels forward when the rear steppingpart 365 c of the forward/reverse switching pedal 365 is applied.

As shown in FIG. 28, the detection mechanism 403 is provided with adetection arm 406 provided on the side of the traveling body 2, and adetection cam 407 provided on the side of the rotation table 201 foroperating the detection arm 406.

The detection arm 406 is provided with an elongated pivoting tab 408,one end part of the pivoting tab 408 is pivotally supported by the upperwall 18 of the main frame 9 of the traveling body 2, an elongated hole408 a is formed in the other end part of the pivoting tab 408, and thepin 405 of the operating tab 404 is inserted into the elongated hole 408a.

Through this configuration, the operating tab 404 is pivoted by thepivoting of the detection arm 406, and the rotation spool 402 a rotatesin conjunction with the pivoting of the operating tab 404. A roller 408b is also provided in a midportion in the longitudinal direction of thedetection arm 406 so as to protrude toward the rotation table 201.

In the inside of the inner race 87 of the rotation bearing 16 providedto the lower wall 214 of the rotation table 201, a cam formation member410 is provided in a state in which the center or rotation thereofcoincides with the rotation axis X of the rotation table 201. Thedetection cam 407 is formed as a cam groove in the cam formation member410. The cam groove has a shape in which three arcs having differentdiameters are gradually connected, and the roller 408 b of the detectionarm 406 comes in contact with the inner surface of the cam groove.

An operating means 411 for operating the pivot locking mechanism 112 isprovided between the rotation table 201 and the machine frame 6 of thetraveling body 2.

As shown in FIGS. 28 and 29, the switch valve 118 of the pivot lockingmechanism 112 is formed by a rotary valve having a rotation spool 412 a,and is provided below the upper wall 18 of the main frame 9 of thetraveling body 2. An operating tab 414 that protrudes in the radialdirection from a rotation shaft is provided to the upper end of therotation spool 412 a so as to protrude further upward than the upperwall 18, and a pin 415 is provided in protruding fashion to the distalend of the operating tab 414.

In the switch valve 118, the rotation spool 412 a is placed in positionA, whereby the communicating oil channel that communicates the twochambers 124A, 124B formed in the cylinder tube 116 of the pivot lockingmechanism 112 are connected, and the two chambers 124A, 124B arecommunicated with each other. The fluid in the circuit can therebyfreely flow in and out of the two chambers. Consequently, the pivotlocking mechanism 112 is released, and the front-wheel axle case 96pivots according to the state of the road surface.

The rotation spool 402 a of the switch valve 402 is placed in positionB, whereby the communicating oil channel is no longer communicated, andthe chambers 124A, 124B of the cylinder tube 116 are blocked. Thepressure oil in the hydraulic circuit is thereby prevented from movingfrom one chamber 124A to the other chamber 124B. The pivot lockingmechanism 112 is thereby activated, and the front-wheel axle case 96 issupported so as to be unable to pivot.

The operating means 411 is provided with an operating arm 416 providedon the side of the traveling body, and an operating cam 417 foroperating the operating arm 416 that is provided on the side of therotation table.

The operating arm 416 has substantially the same configuration as thedetection arm 406, and is provided with an elongated pivoting tab 418.One end of the pivoting tab 418 is pivotally supported by the upper wall18 of the main frame 9 of the traveling body 2, and the pin 415 of theoperating tab 414 is inserted in an elongated hole 418 a formed in theother end of the pivoting tab 418. A roller 418 b is provided in amidportion in the longitudinal direction of the operating arm 416 so asto protrude toward the rotation table 201.

The operating cam 417 is formed by a cam surface formed on the externalperipheral surface in the cam formation member 410, the cam surface hasa shape in which two arcs having different diameters are graduallyconnected, and the roller 418 b of the operating arm 416 is in contactwith the cam surface.

The operating arm 416 is urged toward the rotation axis X by a tensionspring 419 in order to maintain the contact of the roller 418 b with thecam surface.

The operating arm 416 is provided in a position in which the roller 418b thereof is directly opposite the roller 408 b of the detection arm 406via the rotation axis X, and a straight line that connects the centeraxis of the roller 418 b of the operating arm 416, the rotation axis X,and the center axis of the roller 408 b of the operating arm 416coincides with a center axis extending in the front-rear direction ofthe traveling body 2.

The operation of the forward/reverse conversion means 401 and theoperating means 411 will be described using FIG. 29.

First, as shown in FIG. 29A, when the directions of the traveling body 2and rotating body 3 coincide, and the rotation angle of the rotatingbody 3 in relation to the traveling body 2 is 0° (forward orientation),the roller 408 b of the detection arm 406 of the forward/reverseconversion means 401 comes in contact with the large-diameter groovepart 421 a of the detection cam 407, and the roller 418 b of theoperating arm 416 of the operating means 411 comes in contact with onelarge-diameter surface part 422 a of the operating cam 417.

At this time, the detection arm 406 is pivoted in one direction, wherebythe rotation spool 402 a of the switch valve 402 is set to position A,and the remote control valve 373 and the forward-reverse switching means51 are connected in the forward connection state. Accordingly, thetraveling body 2 is caused to travel forward when the front steppingpart 365 b of the forward/reverse switching pedal 365 is applied in thisstate, and although it is the traveling body 2 that actually travelsforward, the swiveling work machine 1 travels forward from theperspective of the operator seated in the driver seat 205.

At this time, the operating arm 416 is pivoted in one direction, wherebythe rotation spool 412 a of the switch valve 118 is set in position A,the two chambers 124A, 124B of the cylinder tube 116 are communicatedwith each other, and the pivot locking mechanism 112 is released. Thefront-wheel axle case 96 is thereby free to pivot, the pair of left andright front wheels 4 move up and down in accordance with the roadconditions, and the orientation of the swiveling work machine 1 isstabilized during travel.

The state of contact of the detection cam 407 with the large-diametergroove part 421 a of the detection cam 407, and the state of contact ofthe operating cam 417 with one large-diameter surface part 422 a of theoperating cam 417 are maintained when the pivot angle of the rotatingbody 3 is within a front pivot range that includes the range form theforward orientation to prescribed pivot angles in the left-rightdirection.

When the rotating body 3 is pivoted until the pivot angle exceeds thefront pivot range, the directions of the traveling body 2 and therotating body 3 are orthogonal to each other as shown in FIG. 29B, forexample, and the pivot angle of the rotating body 3 in relation to thetraveling body 2 is 90°, the roller 408 b of the detection arm 406 comesin contact with a mid-diameter groove part 421 b of the detection cam407, and the roller 418 b of the operating arm 416 comes in contact witha small-diameter surface part 422 b of the operating cam 417.

At this time, the detection arm 406 pivots to a middle state from thestate of pivoting in one direction, whereby the rotation spool 402 a ofthe switch valve 402 is set in position B, and the connection betweenthe remote control valve 373 and the forward-reverse switching means 51is blocked. Accordingly, the traveling body 2 does not travel when thefront stepping part 365 b or the rear stepping part 365 c of theforward/reverse switching pedal 365 is applied in this state.

At this time, the operating arm 416 is pivoted in the other direction,whereby the rotation spool 412 a of the switch valve 118 is set inposition B, the two chambers 124A, 124B of the cylinder tube 116 arenon-communicated, and the pivot locking mechanism 112 is activated,whereby the front-wheel axle case 96 is made unable to pivot. At thistime, since the traveling body 2 is unable to travel, the front-wheelaxle case 96 is fixed in a state in which the pair of left and rightfront wheels are in contact with the road surface and receivesubstantially the same amount of pressure against the ground, and theorientation of the immobile swiveling work machine 1 is therebystabilized.

The state of contact of the detection arm 406 with the mid-diametergroove part 421 b of the detection cam 407, and the state of contact ofthe operating arm 416 with the small-diameter surface part 422 b of theoperating cam 417 are maintained when the rotation angle of the rotatingbody 3 is within a middle rotation range that includes a prescribedrange of rotation angles outside the front rotation range.

When the rotating body 3 is pivoted until the pivot angle exceeds themiddle pivot range, the directions of the traveling body 2 and therotating body 3 are opposite each other as shown in FIG. 29C, forexample, and the pivot angle of the rotating body 3 in relation to thetraveling body 2 is 180°, the roller 408 b of the detection arm 406comes in contact with a small-diameter groove part 421 c of thedetection cam 407, and the roller 408 b of the operating arm 416 comesin contact with the other large-diameter surface part 422 a in theopposite direction from the large-diameter surface part 422 a of theoperating cam 417.

At this time, the detection arm 406 pivots in the other direction fromthe middle state, whereby the rotation spool 402 a of the switch valve402 is set in position C, and the remote control valve 373 and theforward-reverse switching means 51 are connected in the reverseconnection state. Accordingly, the traveling body 2 is operated so as totravel in reverse by applying the front stepping part 365 b of theforward/reverse switching pedal 365 in this state, and although thetraveling body 2 travels in reverse, the swiveling work machine 1travels forward from the perspective of the operator seated in thedriver seat 205.

The operating arm 416 is pivoted in one direction, whereby the rotationspool 412 a of the switch valve 118 is set in position A, the twochambers 124A, 124B of the cylinder tube 116 are communicated with eachother, and the pivot locking mechanism 112 is released.

The state of contact of the detection arm 406 with the small-diametergroove part 421 c of the detection cam 407, and the state of contact ofthe operating arm 416 with the other large-diameter surface part 422 aof the operating cam 417 are maintained when the rotation angle of therotating body 3 is set within the rear rotation range that includes aprescribed range of rotation angles outside the middle rotation range.

Specifically, according to the rotation angle of the rotating body 3,the rotating body 3 is positioned in any rotation range of the frontrotation range, the rear rotation range, and the pair of middle rotationranges provided between the front and rear rotation ranges, theforward/reverse travel operation of the forward/reverse switching pedal365 is switched (inverted), and the pivot locking mechanism 112 isswitched according to the rotation range in which the rotating body 3 ispositioned.

Through this configuration, there is no need to switch the applicationof the forward/reverse switching pedal 365 according to whether therotating body 3 is in the forward orientation or the rear orientation.When the front stepping part 365 b of the forward/reverse switchingpedal 365 is applied, the swiveling work machine 1 travels forward asviewed from the perspective of the operator seated in the driver seat205, and when the rear stepping part 365 c is applied, the swivelingwork machine 1 travels in reverse as viewed from the perspective of theoperator.

The forward connection state of the forward/reverse conversion means 401and the non-operating state of the operating means 411 of the pivotlocking mechanism 112 are maintained while the rotation angle of therotating body 3 is in the front rotation range. Therefore, even when therotating body 3 is rotated in a prescribed angle range from the forwardorientation, there is no switching of the level of the forward/reverseconversion means 401 and the forward/reverse conversion means 401. Thesame applies when the rotating body 3 is in the rear rotation range.

There is a middle rotation range in which the switch valve 402 of theforward/reverse conversion means 401 is placed in a neutral statebetween the front rotation angle range for the forward connection stateand the rear rotation angle range for the reverse connection state.According to this configuration, even when the rotation table 201 ismoved back and forth between the forward orientation and the reverseorientation, there is no tendency for the forward/reverse traveloperation to be inverted by the forward/reverse switching pedal 365 at acertain boundary, and the forward/reverse switching pedal 365 isswitched between forward and reverse travel through a neutral state inwhich travel by the traveling body 2 is impossible. Therefore, operatingerrors caused by forward/reverse travel operation of the forward/reverseswitching pedal 365 during work is prevented.

When the rotation angle of the rotating body 3 is within the middlerotation range, the pivot locking mechanism 112 is operated, andpivoting of the front-wheel axle case 96 is restricted. Consequently,when the rotating body 3 is rotated to perform work, although the centerof gravity moves according to the rotation of the rotating body 3, thefront-wheel axle case 96 does not pivot according to the movement of thecenter of gravity. Therefore, the rotation table 201 does not pivotrelative to the wheel axis case, and a stable work orientation ismaintained during work. Through the operation of the pivot lockingmechanism 112, the front and rear wheels 4, 5 make contact with the roadsurface in a state of substantially equal ground contact pressure.Therefore, even when a large lateral force or moment acts on thetraveling body 2 in conjunction with rotation of the rotation table 201during work, these forces can be resisted by all of the front and rearwheels 4, 5 that support the traveling body 2, and a stable workorientation is maintained during work.

As shown in FIGS. 30 and 31, a steering conversion means 425 havingsubstantially the same structure as the forward/reverse conversion means401 is provided between the power steering controller 367 and thesteering cylinder 97. The connection state of the steering cylinder 97with the power steering controller 367 is thereby switched according tothe rotation angle of the rotating body 3. Consequently, when therotation angle of the rotating body 3 is within the front rotationranger the steering conversion means 425 is placed in the forwardconnection state, and the traveling body 2 is turned to the right whenthe steering wheel 363 is turned to the right.

When the rotation angle of the rotating body 3 is within the middlerotation range, the steering conversion means 425 is placed in theneutral state, and the traveling body 2 cannot rotate according to theoperation of the steering wheel 363.

When the rotation angle of the rotating body 3 is within the rearrotation range, the steering conversion means 425 is placed in thereverse connection state, and the traveling body 2 is turned to theright when the steering wheel 363 is turned to the right. At this time,the direction in which the steering wheel 363 is turned, and the turndirection of the traveling body 2 are the same as viewed from theperspective of the operator seated in the driver seat 205, and operatingerrors due to steering wheel operation during work is prevented.

An embodiment of the present invention was described in detail, but thepresent invention is not limited by the embodiment described above. Forexample, the same effects as the embodiment of the present invention aredemonstrated when the pair of left and right rear wheels 5 are pivotablysupported by the traveling body 2 via a wheel axle case as in the caseof the left and right front wheels 4.

Specifically, the wheel axle case and the pivot locking mechanism 112 ofthe present embodiment may be provided to one or both of the left andright front wheels 4 and the left and right rear wheels 5.

The same effects as those of the present embodiment are alsodemonstrated when the detection arm 406 of the detection mechanism 403is provided on the side of the rotating body 3, and the detection cam407 is provided on the side of the traveling body 2. The effects of thepresent embodiment are also demonstrated when the operating arm 416 ofthe operating mechanism is provided on the side of the rotating body 3,and the operating cam 417 is provided on the side of the traveling body2.

A configuration may also be adopted in which a hand accelerator lever isprovided to the steering device 202, and the speed of the engine 7 isadjusted by the hand accelerator lever according to the type of workperformed by the ground implement.

A configuration may also be adopted in which a travel lock valve isprovided between the charge pump and the remote control valve 373 tostop the pilot pressure from being fed to the remote control valve 373from the charge pump.

The embodiment above was described using the example of a wheeled workmachine provided with a rotation table 201 and an excavating implement203, a driver seat 205, and other components provided on the rotationtable 201, but the rotation table 201 is not an essential constituentelement. For example, a different configuration may be adopted in whichthe excavating implement 203, the driver seat 205, and other componentsare provided directly to the traveling body 2.

INDUSTRIAL APPLICABILITY

The present invention can be utilized in a wheeled work machine in whichan engine is mounted at the rear of a machine frame supported by frontand rear wheels, and the wheeled work machine is provided with atraveling body having a traveling system power transmission mechanismfor transmitting power from the engine to the rear wheels.

1. A wheeled work machine comprising a traveling body having an enginemounted at a rear part of a machine frame supported by front and rearwheels, and a traveling system power transmission mechanism fortransmitting power from said engine to the rear wheels; wherein saidtraveling system power transmission mechanism has a rear wheeldifferential device disposed in front of the engine, a hydrostatictransmission that is disposed in front of the rear wheel differentialdevice and receives power from the engine, and a mechanical transmissiondevice that is disposed between said hydrostatic transmission and saidrear wheel differential device and transmits power from said hydrostatictransmission to said rear wheel differential device; said wheeled workmachine further comprising: a traveling drive shaft extending forwardfrom the engine for receiving power from the engine; an input shaftextending rearward from the hydrostatic transmission for inputting powerfrom the engine to the hydrostatic transmission; and an output shaft foroutputting power from the hydrostatic transmission, wherein thetraveling drive shaft and the input shaft are coaxially interconnectedand extend parallel with the output shaft, and wherein said engine, saidrear wheel differential device, said mechanical transmission device, andsaid hydrostatic transmission are formed integrally with each other. 2.The wheeled work machine according to claim 1, wherein a housing thataccommodates said rear wheel differential device is attached and fixedto a front surface of said engine; a transmission case that accommodatessaid mechanical transmission device is attached and fixed to a frontsurface of said housing; and a casing for said hydrostatic transmissionis attached and fixed to a front surface of said transmission case. 3.The wheeled work machine according to claim 2, wherein said powertransmission mechanism has left and right final transmission devices fortransmitting power from left and right differential output shafts ofsaid rear wheel differential device to rear wheel axles on same left andright sides; wherein final transmission cases that accommodate saidfinal transmission devices are attached and fixed to said housing. 4.The wheeled work machine according to claim 3, comprising a rotationtable supported so as to be able to swivel on said traveling body;wherein a ground implement is provided to a front part of said rotationtable; and a driver seat is provided to a rear part of said rotationtable.
 5. The wheeled work machine according to claim 4, said machineframe having: an upper wall and left and right side walls that extenddownward from left and right ends of the upper wall; an enginepositioning part for positioning said engine at a rear part between saidleft and right side walls; a travelling power transmission systempositioning part for positioning said housing, said transmission case,and said casing in front of said engine between the left and right sidewalls; and a bearing positioning part for positioning a swivel bearingfor supporting the rotation table in a substantial center positionbetween front and rear axles; wherein a case fitting part for fittingwith the final transmission cases from above is formed at rear parts ofsaid left and right side walls.
 6. The wheeled work machine according toclaim 1, wherein a rear wheel axle that receives power from thedifferential output shafts of said rear wheel differential device androtates the rear wheels is provided behind the differential outputshafts so as to overlap said engine as viewed from the side.
 7. Thewheeled work machine according to claim 1, further comprising: a bevelpinion shaft extending parallel with the output shaft for receivingpower from the output shaft; wherein a rear end of the bevel pinionshaft is positioned more rearward than a rear end of the output shaft,the rear wheel differential device is positioned rearward of the bevelpinion shaft, and power from the output shaft is inputted to the rearwheel differential device via the bevel pinion shaft.
 8. The wheeledwork machine according to claim 1, wherein a rear end of the input shaftprotrudes rearward from a rear side of a casing for the hydrostatictransmission; and a front end of the output shaft protrudes forward froma front side of the casing and a rear end of the output shaft protrudesrearward from the rear side of the casing.